Single element printing head



July 21, 1959 J. E. HICKERSON ET AL SINGLE ELEMENT PRINTING HEAD 2 Sheets-Sheet 1 Filed Nov. 17, 1955 INVENTORS JOHN E. HICKERSON RALPH E. PAGE ES A.

IDENHAMMER I (Um A TORNEY July 21, 1959 J. E. HICKERSON ET AL 2,895,584

SINGLE ELEMENT PRINTING HEAD 2 Sheets-Sheet 2 Filed Nov. 1'7, 1955 Fl G 2 FIG. 4

mv Powm FIG. 7

United States Patent SINGLE ELEMENT PRINTING HEAD John E. Hickerson, Wappingers Falls, and Ralph E. Page and James A. Weidenhammer, Poughkeepsie, N .Y., assignors to International Business Machines Corporation, New York, N.Y., a corporation of New York Application November 17, 1955, Serial No. 547,481

13 Claims. (Cl. 197-52) This invention relates to printing mechanisms and more particularly to an improved single element printing head for a typewriter or similar machine.

By definition, a single element printing head is a device wherein all the characters of a type font are positioned or formed on the surface of one printing element; which element is positioned for printing engagement with a paper carrier after a selected character of the type font has been moved to printing position.

Single element printing mechanisms have the distinct advantage of being a high mass low velocity printing source, which fundamentally have a low noise level in comparison to the conventional light weight high velocity type bars employed in a typewriter. It follows therefore that a conventional single element typewriter is a great asset in producing a quiet typing action, and accordingly it is a first object of this invention to provide an improved single element printing head for a typewriter.

It is a further object of this invention to provide an improved interchangeable shell for a single element printing head wherein the type font may be interchanged with a minimum effort.

Admittedly, single element printing devices are not new in the art, since they have :been known in the form of wheels, sectors, cylinders, or segments; but the size and shape of these devices presented certain complications and disadvantages, and they could not be classified as a commercial success. One specific problem with them was that the balance of mass behind a character being printed was not uniform. For example, if a cylindrical printing element was used of the type shown in U. S. Patent Carroll 2,320,810 which cylindrical element is shifted axially to present a predetermined row to printing position, then the mass behind a character in the upper row would be less than the mass behind a character in the lower row. It follows therefore, that the printing density changes in accordance with the row of the type on the type element. It is a further object of this invention, therefore, to provide an improved printing element wherein the mass behind each printed character is substantially uniform.

It is a still further object of this invention to provide a single element printing mechanism which strikes squarely against the platen with no tendency to slide or smudge the print.

A still further object of this invention is to provide a single element printing head preferably in the form of a truncated sphere or ball having a short radius for maximum type clearance, thereby preventing marking by a character adjacent to the one being printed.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

Briefly, this invention relates to a single element printing head in the form of a truncated sphere or ball wherein the characters are arranged on the face of the printed element in rows and columns with only one character at a time in printing position. The printing element has a hollow shell which is removably supported by a system of internal gimbals and bearings. The center of mass of the supporting mechanism is located substantially at the center of the sphere to provide a uniform mass behind each print stroke, irrespective of the character being printed. Provision is made for rotating and tilting the print element whereby one character at a time may be presented to a single printing position.

Referring to the drawings:

Fig. 1 is a perspective view of a single element printing mechanism.

Fig. 2 is a side elevation of the single element printing mechanism shown mounted for printing engagement with a typewriter platen.

Fig. 3 is a diagrammatic view of the geometry of operation of the single element printing head in cooperation with a platen.

Fig. 4 is a front elevation of a character on the single element printing head.

Fig. 5 is an exploded view of a preferred embodiment of the single element printing mechanism.

Fig. 6 is a sectional view of a second embodiment of the single element printing mechanism.

Fig. 7 is a development view of the periphery of the type element.

In the drawings, a single element printing head 2 is shown (Fig. 2) supported by a tube, or hollow post 3 on a carrier 4 for pivotal movement about a hollow trunion 6 into and out of printing engagement with a platen 8.

While the member 4 is called a carrier, it is apparent that either the carrier 4 may be movable relative to the platen 8, or the platen 8 may be movable relative to the carrier 4 to provide conventional character spacing.

In a preferred embodiment, all the required characters of a type font (upper and lower case) are formed on the peripheral surface of a spherical shell 9 which is a portion of the printing element 2 (Fig. 7). Assuming the shell 9 is divided by a vertical plane, then the lower case characters are positioned on one hemisphere of the shell and upper case characters are positioned on the other hemisphere.

The spherical shell 9 is removably secured to an internal supporting mechanism. The sphere is truncated and closed at its upper end 10 to provide a bearing surface, and it is truncated and open at its lower end 12 in order to provide clearance for the required tilting of the head relative to the vertical support post 3, whereby any selected row of characters may be located at a predetermined printing position.

With particular reference to the exploded view of Fig. 5, the post 3 is shown supporting a base member or yoke 16 having spaced apart vertical arms 18, 20 which accommodate respectively bearing pins 22a, 24a mounted on plates 22, 24. The bearing pins 22a, 24:: form a tilt axis for a somewhat cylindrical rocker, or mounting block 26. More specifically, bearing pins 22a and 20a may be passed through aligned apertures 18a and 20a in the arms of yoke 16, and into a bore 28 formed through the mounting block 265.

In order to provide" a mechanism for indexing or tilting block 26, a hollow tilt shaft 30 is passed through an axial bore 32 of the yoke 16 while a shaft flange 34 acts as a bearing collar riding on the upper surface of the yoke .16. The .tilt shaft 30 carries a sector of a 3 42 of the'block 26. The tilt plate 40 has a bearing opening 44 in alignment with the'bore 28 inthe'block 26, which bearing 44 will accommodate the bearing pin 22a.

To assemble this mechanism, the tilt shaft is installed in the bore 32 of yoke 16, and then the'tilt plate 40- block 26 assembly is slid between arms 18, 20of yoke 16, so that gear sectors 36, 3.8 are meshed; then the pins 22a and 24a of the bearing plates 22 and 24 respectively are slid through the aligned openings 18:: and 20a respectively (with pin 22a also passing through been ing 44 of tilt plate 40 and pin 24a passing through a bore in a detent plate 88, later described) to engage the bore 28 of the block 26. The plates Hand "24 are then secured to the yoke by the screws 46 and 48. It is obvious that with this construction, the rotation of the tilt shaft 30 acting through the meshing gear sectors 36 and 38 will cause tilting of the rocker 'or mounting block 26 about the axis of the tilt pins 22a and 24a.

In addition to tilting the head, provision must also be made for indexing or rotating it, andthis rotation is accomplished by the following structure. More specifically, a turn or rotation shaft 50 is passed axially through a central bore 52 of the tilt shaft 30 before the mounting block 26 is assembled on yoke. The rotation shaft 50, Fig. 5, is provided with a collar 51 having an internal bore 53 suitable to accommodate a lower end of a dumb bell 54 which is a part of a universal drive. A pin 56 is passed through suitable bores 58 in collar 51 and through a groove 60 in'the lower end of the dumb bell '54 to provide a driving connection between the rotation shaft 50 and the dumb bell 54.

Mounting block 26 is further provided with a central axial bore 62 large enough to accommodate both the collar 51 and a corresponding collar 64, a part of a rotatable flanged member, or upper plate 66. When the upper plate 66 is installed on the mounting block 26' the.

upper end of dumb bell 54 lies within collar 64, and a pin 68 is passed through a bore 70 to ride-in a groove 72 in the upper end of the dumb bell 54. The upper plate 66, (which fits in a counter bore 67 in block 26) in turn is held in engagement with the mounting block 26 by means of the securing plate 73 which is fastened by means of screws 74 to the mounting block 26. With this arrangement of parts, rotation of the shaft 50 acting through the pin 56 and dumb bell groove 60 causes the rotation of dumb bell 54 which in turn, acting through the pin 68 and dumb bell groove 72 produces rotation of the upper plate 66 relative to the supporting block 26. It should be noted that with the dumb bell type universal coupling, a uniform angular drive is provided for upper plate 66 irrespective of the tilt of the supporting block 26 relative to the support pins 22a and 24a.

In order to assemble the shell 9 on its supporting mechanism, the shell is provided with an internal bore 14 which is slightly larger than the maximum diameter of the mounting block 26. The upper end 'of shell 9 is further provided with a'bore 76 through-which a stud 78 integral with the upper plate 66 may be passed, and accordingly the shell 9 and stud 78 along with block 26 may be described as having an interfitting relationship (with ends of pin 68 engaging a complementary groove 81 in shell-9 thereby insuring a positive driving relation ship). The shell 9 may be removably secured to the upper plate 66 via screw 79. With this construction, the shell 9 which may be interchanged readily is tiltable with, and rotatable relative to the supporting block 26.

In order to insure alignment of acharacter on the printing element with any reference position, a detent mechanism is provided. The rotation or turning detent comprises aplurality of semi-spherical .ball sockets 80 spaced about the periphery of bore 14 of the shell 9. A ball 82 is spring biased into engagement with the ball sockets 80 by means of a spring 84 which is,mounted in asocket 86 formed in the mounting block 26.

The tilt detent used to align a predetermined row of characters with areference position comprises the detent be engaged one at a time by the ball 92, which in turn is biased by the spring 94 mounted in a bore 96 formed in-the upper surface of the yoke 16. The detent teeth 91 are so positioned, that when the valley between two of them is engaged by ball 92, a corresponding print row formed on type element 2 will be aligned with a reference position. The detent mechanism insures accuracy while permitting looseness in the drive system.

With the mechanism assembled as shown in Figs. 1 and 2, the tilt shaft 30 and the turn shaft 50 extend below and coaxially-of the supporting tube 3. To facilitate turning of these shafts, a pair of pulleys 94,96 are .se-.

cured to the shafts 30, 50 respectively. The pulleys may then be connected to some driving means (not shown), such as the flexible strand system shown in copending application Serial No. 547,482 filed Nov. 17, 1955 and U.S. Patent 2,757,775.

The flexible strand system permits indexing of the pulleys to position a predetermined character of the print element at a reference position.

Particular attention is drawn to the fact that the supporting trunnion 6 of the carrier 4 is so positioned with respect to the platen 8, and the peripheries of pulleys 94, 9,6 that the following objectives are attained.

First, the character being printed moves radially into engagement with the platen, and the point of impactis at high dead center of the motion of the printing element, wherein the line of impact force (x-x; Figs. 2 and 3) passes through the spheric center of the type element and thecenter of the platen. This action assures a direct print blow with little danger of smudging.

Second, the flexible strand system which is employed to index the pulleys will twist only about its longitudinal axis thereby assuring a long strand life.

It should be noted that in view of the characters being arranged in a plurality of rows about the surface of a sphere, the latter may be of short radius thereby giving a maximum platen clearance between characters adjacent the one being printed.

With reference to Fig. 3, one of the characters on the printing element 2 is shown as a pyramidal section having an apex at the center of the sphere. A major portion of the mass of the printing mechanism will also be centered at this point, and accordingly, irrespective of the degree of tilt of the element 2, the character being printed always has substantially the same mass behind it, and accordingly, the printing mechanism tends to produce a uniform printing density. Incidentally, it has been found that, because of the high mass of the printing element, the relative size of the character being printed is of minimum importance with respect to uniform color density.

Alternate embodiment In an alternate embodiment of the print head (Fig. 6) a supporting tube or post 104 carries an integral base member yoke 106 having arms 105, 107. A pivot pin 108 is supported in the upper end of the arms 105, 107. A hollow tilt shaft 110 which carries a tilt gear 112 is passed axially through post 104. The tilt gear 112 is engageable with a complementary tilt gear sector 114 which is an integral portion of a tilt member or supporting frame 116 that is supported for tilting movement about the tilt pin 108. With this arrangement of parts the turning of the tilt shaft 110 causes pivoting of the tilt gear sector 114 to rock the supporting frame 116 about the tilt pin 108. The supporting frame 116 has a bore 118 which accommodates a boss 117 extending axially from a hollow cylindrical member 119.

A turn shaft 120 is supported coaxially of post 104 and lies within tilt shaft 110. A turn gear 122 is mounted on the upper end of turn shaft 120 to mesh with an idler 124 supported for free rotation about the pivot pin 108. The idler 124 in turn is meshed with a turn pinion 126 which has a stub shaft or bushing 128 which carries an internal bore 130 for accommodating a screw 132 used to secure a spring washer 134 to the support frame 116. A truncated spherical shell 136 having print characters arranged on the peripheral surface thereof is slid over cylinder 119 which has a bottom flange 138. Then the spring Washer 134 will hold the spherical shell 136 in place. With this arrangement of parts, the turning of the shaft 120 causes turning of gear 122; the idler 124; and the consequential rotation of the bevel gear 126. This action causes rotation of the truncated spherical shell 136. Obviously, detent means could be provided for alignment, as in the preferred embodiment. I

It follows therefore that either a universal drive or a gear system as shown in the alternate embodiment will operate satisfactorily to rotate and tilt the single element print head. The important point is to locate a major portion of the suporting and driving mass within the print head and preferably as close as possible to its center thereby insuring a uniform mass behind each print stroke.

While there have been shown and describel and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions .and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is'the intention therefor to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A single element printing head comprising a base member, a tilt member, pivot means pivotally supporting said tilt member relative to said base member, a rotatable member, means mounting the same for rotation relative to and coaxially of said tilt member, a type shell having a plurality of type characters arranged on the periphery thereof, means mounting the same on said rotatable member, indexing means, and means interconnecting said indexing means with said tilt member and with said rotatable member respectively to provide for the operation of said connected members and the consequential movement of said type shell whereby one shell character at a time may be positioned at a reference position in response to the manipulation of said indexing means.

2. A single element printing head comprising a yoke, a tilt member, pivot means carried by the arms of said yoke for pivotally supporting said tilt member, a rotatable member, means mounting the same for rotation relative to said tilt member, a pair of shafts passing through said yoke, means interconnecting one of said shafts to said tilt member, and the other to said rotatable member to provide for the actuation of said members through the operation of said shafts, a hollow type shellsurrounding said tilt member and having bearing means for engaging said rotatable member, and a plurality of type characters arranged on the peripheral surface of said shell whereby through the manipulation of said shafts one type character at a time may be located at a reference position.

3. A single element printing head comprising a yoke, a tilt member, pivot means carried by the arms of said yoke for pivotally supporting said tilt member, a rotatable member, means mounting said rotatable member for rotation relative to and coaxially of said tilt member, indexing means mounted in said yoke, means interconnecting said indexing means with said tilt member and with said rotatable member respectively to provide for the actuation of said members through the operation of said indexing means, a type shell having a plurality of type characters arranged thereon, and means securing.-

said shell to said rotatable member whereby selected characters may be positioned at a reference position in response to the manipulation of said indexing means.

4. A single element printing head comprising a yoke, means supporting the same for movement from a rest position to a printing position, a tilt member, pivot means carried by the arms of said yoke for supporting said tilt member for tilting movement relative to said yoke, a rotatable member carried by said tilt member, a pair of shafts passing through said yoke, means interconnecting said shafts to said tilt member and said rotatable member respectively, a type shell in the form of a hollow sphere, means attaching said shell to said rotatable member for movement therewith, and a plurality of type characters arranged on the peripheral surface of said shell in parallel rings and spaced apart columns whereby through the manipulation of said shafts, one type character at a time may be moved to a reference position.

5. A single element printing head comprising a yoke, means supporting the same in an operative position, a tilt member, pivot means carried by the arms of said yoke for supporting said tilt member for tilting movement, a rotatable member, bearing means supporting the same for rotation relative to said tilt member, a pair of shafts passing through said yoke and having connections to said tilt member and said rotatable member respectively, a. type shell in the form of a hollow truncated sphere having one truncated end provided With a surface engaging said rotatable member, means for clamping said shell to said rotatable member said truncated sphere enclosing said yoke and tilt member to be tiltable relative to said:

yoke in response to tilting of said tilt member and to be rotatable with said rotatable member relative to said yoke, and a plurality of type characters arranged on said shell in parallel rings and spaced apart columns whereby through the manipulation of said shafts, one type character at a time is moved to a reference position.

6. A single element printing head comprising a yoke, means supporting the same for movement from a rest position to a printing position, a tilt member, pivot means supporting said tilt member for tilting movement relative to said yoke, a rotatable member carried by said tilt member, a pair of concentric shafts passing axially through said yoke and having connections to said tilt member and said rotatable member respectively, a. type shell, a plurality of type characters arranged on said shell in parallel columns, means supporting said shell on said rotatable member thereby providing for both pivotal and rotating movement of said shell relative to said yoke, and rotation detent means for holding one column of said shell at a time in a reference position.

7. A single element printing head comprising in com bination, a yoke means supporting the same in an operative position, a tilt member, pivot means supporting said tilt member for tilting movement relative to said yoke, a rotatable member carried by said tilt member, a tilt shaft and a rotation shaft passing through said yoke, means interconnecting said shafts with said tilt member and said rotatable member respectively, said rotatable member interconnecting means permitting rotation of said rotatable member irrespective of the degree of tilt of said tilt member, said tilt member interconnecting means comprising a tilt gear sector connected to said tilt 8. A single element printing head comprising in combination, a yoke, means supporting the same in an operative position, a tilt member, pivot means supporting said tilt member for tilting movement relative to said yoke, a rotatable flange member carried by said tilt member, a tilt shaft and a rotation shaft passing through said yoke, means interconnecting said shafts with said tilt member and said rotatable flange member respectively, said rotatable flange member interconnecting means permitting rotation of said flange member irrespective of the degree of tilt of said tilt member, said tilt member interconnecting means comprising a tilt gear sector connected to said tilt member, a meshing gear interconnecting said tilt shaft and said tilt gear sector, a type shell, a plurality of type characters distributed about said shell in parallel rings and spaced apart columns, means supporting said shell on said rotatable flange member thereby providing for both pivotal and rotating movement relative to said yoke, rotation detent means for holding one column of said shell at a time in a reference position, and tilting detent. means for holding one ring of said shell at a time in a reference position whereby through the manipulation of said shafts, one type character at a time may be positioned at a reference position.

9. A single element printing head comprising in combination, a yoke, means supporting the same for movement from a rest position to a printing position, a tilt member, pivot means carried by the arms of said yoke for supporting said tilt member for tilting movement relative to said yoke, a rotatable flange member carried by said tilt member, a tilt shaft and a rotation shaft passing through said yoke, means interconnecting said shafts with said tilt member and said rotatable flange member respectively, said rotatable flange interconnecting means comprising a universal type coupling permitting rotation of said rotating flange member irrespective of the degree of tilt of said tilt member, said tilt member interconnecting means comprising a tilt gear sector connected to said tilt member, a meshing gear interconnecting said tilt shaft and said tilt gear sector, a type shell in the form of a hollow truncated sphere having one truncated end provided with bearing means to receive said flange member, said truncated sphere enclosing said yoke and said tilt member, to be tiltable relative to said yoke in response to tilting of said tilt member and to be rotatable with said rotatable flange relative to said yoke, and a plurality of type characters arranged on said shell in parallel rings and spaced apart columns whereby through the manipulation of said shafts one type character at a time is moved to a reference position.

10. A single element printing head comprising in combination, a yoke, means supporting the same for movement from a rest position to a printing position, a tilt member, pivot means carried by the arms of said yoke for supporting said tilt member for tilting movement relative to said yoke, a rotatable flange member carried by said tilt member, a tilt shaft and a rotation shaft passing through said yoke, means interconnecting said shafts with said tilt member and said rotatable flange respectively, said rotatable flange interconnecting means comprising a universal type coupling which is operable to cause rotation of said flange irrespective of the degree of tilt of said tilt member, said tilt member interconnecting means comprising a tilt gear sector connected to said tilt member, a meshing gear interconnecting said tilt shaft and said tilt gear sector, a type shell in the form of a hollow truncated sphere having one truncated end provided with bearing means to receive said rotating flange, said truncated sphere enclosing said yoke and rocker to be tiltable relative to said yoke in response to tilting of said tilt member and to be rotatable with said rotatable flange relative to said yoke, a plurality of type characters arranged on said shell in parallel rings and spaced apart columns, rotation detent means for releasably holding one column of said shell at a time in a reference position comprising a ball and spring car- 8 ried bysaid yoke, and a plurality of ball sockets defined by the inner surface of said sphere to be engageable one at a time with said ball, and a tilting detent for holding one ring of said shell at a time in'a reference position whereby through the manipulation of said shafts, one type character at a time is moved to a reference position.

11. A single element printing head comprising a yoke, a tilt member, pivot means supporting said tilt member on the arms of said yoke, a rotatable flange member, means mounting the same for rotation relative to said tilt member, a hollow type shell having type characters arranged on theperipheral surface thereof, means mounting said shell on said flange member for rotation and tilt relative to' said yoke, and indexing means for actuating said flange member and said tilt member comprising a pair of concentric shafts passing axially through said yoke, bevel gear meansinterconnecting one of said shafts with said tilt member to provide for the tilting thereof, and differential gear means interconnecting the other of said shafts with said rotatable flange member to provide for the rotation thereof.

12. A single element printing mechanism comprising, in combination, a base member, a tilt member, means pivotally supporting said tilt member on said base member, a rotatable member, means mounting said rotatable member on said tilt member coaxially of the latter and for rotation relative thereto, a type shell in the form of a hollow truncated sphere and having a plurality of type characters arranged on its periphery, means mounting said type shell on said rotatable member, indexing means, means interconnecting said indexing means with said tilt member and said rotatable member respectively to provide for the operation of said connected members and the consequential movement of said type shell whereby one character at a time may be positioned at a reference position in response to the manipulation of said indexing means, means supporting said base member for pivotal movement about a horizontal axis, and a cylindrical platen engageable by the one of said characters in reference position on the moving of said base member about said horizontal axis, the arrangement of said platen and said shell being such that a tangent to each at the time of printing intersects and is perpendicular to, said horizontal axis.

'13. A single element printing mechanism comprising, in combination, a base member, means supporting said base member for pivotal movement about a horizontal axis, a tilt member, means mounting said tilt member on said base member for pivotal movement about an axis extending parallel to said horizontal axis, a type shell in the form of a hollow truncated sphere, type characters formed on the outer surface of said shell, means mounting said type shell on said tilt member so that the center of the shell lies in the axis about which said tiltmember is movable, means supported by said base References Cited in the file of this patent UNITED STATES PATENTS 477,224 Pratt June 21, 1892 631,833 Treadgold Aug. 29, 1899 892,891 Richards July 7, 1908 2,207,874 Reynolds July 16, 1940 FOREIGN PATENTS 9,069 Great Britain Apr. 26, 1906 

